I have a basic shack consisting of a VX7 and a few antennas. I will be adding to this collection as time and budget allows. With this meager beginning and your help I am hoping to stop an inconsiderate neighbor. I have recently lost three plants from my front yard in the past 2 weeks. They have been ground planted hydrangeas pulled out of the ground. Does anyone know of a simple and small fox that could be placed in the root ball that would send out a small but detectable signal? It would need to be waterproof and run for a number of days and a small battery. If anyone has any ideas, I would love to hear them. I will be adding a CCTV camera to the area, but being able to track the plant would be very helpful as well. If I actually catch the culprit, it would make a very amusing article. (Amateur Radio used to solve a criminal nuisance problem)Thank you for your time.P

It depends how complicated you want to get, what sort of range you need, and how largethe plants are. (We have hydrangeas that are large enough to insert the tracker into ahole in the trunk. But more likely you are dealing with much smaller plants if the neighborsare making off with them.)

A deluxe solution might be to use one of the APRS trackers sold for balloon launches and such -they include a GPS unit to send their current position, and if there are within range of a digipeateryou can track the plant across the country. Like this:

You can build such a device for 2m just as easily, and adding crystal control isn't too difficult.However, a simple crystal oscillator is probably easier (without the microphone circuit). Thehard part is finding suitable crystals, but baud rate crystals that multiply up to 147.456 MHz(fundamentals of 12.288 MHz, 8.192 MHz, 16.384 MHz, etc.) are stock items in mostelectronic catalogs. A 16 MHz crystal oscillating on the 9th overtone will hit the 2m bandwith just one stage. Such a stage can be powered by a 9V battery, or a small hearing-aidsize cell if one wants to get quite small.

To allow the battery to last longer, add a CMOS 555 timer chip that pulses the signal at alow duty cycle. This does make it more difficult to hunt, but can extend the useful life by10X or more. You'll have to see how long it takes your radio to register a signal and displaythe signal strength, and make sure that your transmit pulses are at least that long (or lookfor a local ham with better equipment that will help you.)

There are also some 433 MHz transmit chips available that would make it easier to buildsomething for that band - the higher the frequency, the smaller the antenna for the same gain and/or directivity.

Suitable antennas can be built quite cheaply using WA5VJB's "Cheap Yagi" methods here:

I had a problem with trash cans disappearing. I set a box in the bushes that contained an old siren, a battery, and a micro-switch with a pull pin. A piece of thread went from the pull pin to the trash can. Next time someone grabbed the can the siren went off. I found the can laying there with the siren running and never had another missing can.

Since you know its a neighbor why not get a picture of them for the police? Go to your local sporting goods store and buy a trail camera. These cameras are used for showing if deer are in a particular area. They are not all that expensive and its pretty hard to lie when you have pictures of the person.

For shorter range work (for example, if you can walk around sniffing for the plant to confirm that one your neighbor had planted came from your yard) there was a circuitin Scientific American back around 1970 for a pulsed AM BC oscillator using asingle transistor. This probably could be built for various ham bands as well, thoughthe frequency accuracy is likely to be rather loose. (Especially while travelingthrough a dog's digestive tract, as happened in one application - the timing of thepulses served as an indicator of temperature variations.)

A similar oscillator could be made using a small crystal on HF: it might not transmit forvery far, but could be detected from a few feet away. DF in the conventional sensemight be more difficult ( a hand-held yagi isn't very practical at 10 MHz, but I makehand-held 80m DF receivers using loop antennas) but you could simply sniff aroundfor maximum signal strength.

Unfortunately I don't have a specific circuit to point you to, but if you can give mean idea of the expected distance over which you need to be able to hear the signalthen I can give it some thought - I've built a few such low level signal sources in the past for testing receivers, etc.

One thing to watch about the 'game' cameras. Make sure it has TRUE IR night vision. Most will say they have that, but make sure it is NOT visable to the human eye. Newer, more expensive ones will work.How do I know? The crooks saw the flash and took the camera!!!!

If you insist on "planting" a transmitter, falconry transmitters may be what you need. They're relatively small and long range.

However, I don't know if planting a transmitter and tracking the plant is the best idea. If I was morally corrupt enough to steal other people's plants, and was confronted, I would not hesitate to lie to the police, and insist that you trespassed on my property and planted the radio transmitter on my plant. I'm sure stealing back the plant will have its own set of consequences. (Remember what happened to OJ Simpson for stealing back his sports memorabilia?)

I concur with others about the video camera. Having good video evidence, and letting the proper authorities use that evidence, is probably the most reasonable course of action. If you must use amateur radio for solving this issue, why not set up some hidden cameras using ATV as back haul to your recording setup. Part 15 900MHz video transmitters can be modified for ATV relatively easily.

Are you sure that whatever is removing the plant is of the human variety? My XYL went out to the garden one morning a couple of years ago to discover that her tomato plants were disappearing into the ground. After some research we concluded that the culprit was probably a vole (as opposed to a mole.) Also, I don't know where you live, but at this semi-rural QTH if it's not fenced there's a possibility deer or other animals may decide it's a snack, or in the case of dogs, that it needs to be "relocated".

That being said, a simple system which would give whomever (or whatever) a nice non-lethal tingle or set off an alarm would probably get the message across HI HI!!

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